Refrigerator freezer with frost eliminator

ABSTRACT

A refrigerator-freezer having a forced air circulation system wherein the air is cooled by the evaporator and circulated by fan means to and from side-by-side refrigerator and freezer compartments. Control means maintain the air in the refrigerator compartment above 32* F. and the air in the freezer compartment below 32* F., and duct means, including a Venturi nozzle, are provided for combining the air flows in the freezer compartment such that moisture in the return air from the compartments is frozen into crystallized water while airborne by refrigerated air diverted from the evaporator chamber outlet. The crystallized water is separated therefrom while airborne prior to the combined air flows returning to the evaporator. Collecting means are provided for melting and evaporating the water outside of the freezer compartment.

United States Patent 1 Jacobs REFRIGERATOR FREEZER WITH FROST ELIMIN ATOR [75] inventor: James W. Jacobs, Dayton, Ohio [73] Assignee: General Motors Corporation,

Detroit, Mich.

[22] Filed: May 3, 1974 [21] Appl. No.: 466,684

July s, 1975 [57] ABSTRACT A refrigerator-freezer having a forced air circulation system wherein the air is cooled by the evaporator and circulated by fan means to and from side-by-side refrigerator and freezer compartments. Control means maintain the air in the refrigerator compartment above 32 F. and the air in the freezer compartment below 32 F., and duct means, including a Venturi nozzle, are provided for combining the air flows in the freezer compartment such that moisture in the return air from the compartments is frozen into crystallized water while airborne by refrigerated air diverted from the evaporator chamber outlet. The crystallized water is separated therefrom while airborne prior to the combined air flows returning to the evaporator. Collecting means are provided for melting and evaporating the water outside of the freezer compartment.

3 Claims, 6 Drawing Figures PATENTEUJUL 8 ms SHEET lllllllll IV AW PATH-#TEDJUL 8 I975 SHEET 1 3i 3 o o a 2 @d @Lu w u MTFNTEDJUL 8 ms 3 W sum 3 L Q) L FLT: @17 l Ii """i* gfil i BUTTER-Comm ER FROST MELT [5a {5 1 REFRIGERATOR FREEZER WITH FROST ELIMINATOR This invention relates to refrigeration apparatus and is directed to a domestic refrigerator having above and below freezing compartments whereby a large portion of the moisture from the air before it passes over the evaporator is removed, thereby substantially reducing the need to defrost the evaporator.

It is an object of this invention to provide improved refrigerating apparatus comprising side-by-side frozen food and fresh food chambers, a refrigeration system for cooling a quantity of air to below-freezing by passing it through an evaporator flow chamber. duct means dividing the quantity of cooled air into a first portion and lesser second portion, subsequently dividing the first portion into a third and lesser fourth portion, a blower system for circulating the third portion in the freezer chamber and the fourth portion in the fresh food chamber thereby raising the fourth portion to a temperature above-freezing, duct means including a Venturi nozzle for recombining the second and fourth portions in the freezer chamber to below-freezing temperature, whereby moisture is frozen or condensed in solid form while airborne; duct means for subsequently recombining the third portion with the recombined second and fourth portions to further reduce the temperature and solidify additional moisture therefrom; and collecting means for separating the solidified moisture from the air stream and returning the recombined quantity to the evaporator chamber for cooling.

Other features and advantages of the invention will be apparent from the following description of one embodiment of the invention, considered in conjunction with the accompanying drawings wherein:

FIG. 1 is a semi-diametric front elevation of a refrigeration apparatus embodying the invention, with the doors to the different compartments omitted;

FIG. 2 is a vertical sectional view taken on the lines 22 of FIG. I;

FIG. 3 is a fragmentary enlarged front elevational view with portions broken away to facilitate illustration of the invention;

FIG. 4 is a fragmentary vertical section view taken substantially on the line 44 of FIG. 3;

FIG. 5 is a schematic diagram of a portion of the control circuit illustrating the control of the optional frost melt assist heater of the refrigeration apparatus, and

FIG. 6 is an enlarged view taken on line 6-6 of FIG. 3 of the frozen moisture separating device.

Referring now to the drawings a refrigerator of the present invention comprises an insulated cabinet 10, the outer shell of which has top and bottom walls 12 and 14, sidewalls l6 and I7 and a rear wall 18. The interior of the cabinet 10 has an upright insulated center partition wall which divides the interior into an above-freezing temperature fresh food chamber or compartment 21 on the right and below-freezing temperature frozen food or freezer compartment 22 on the left arranged in a side-byside manner. The compartments are closed by separate insulated doors as door 19 shown in FIG. 2 closing compartment 22.

The refrigeration of the compartments is effected by the flow of the refrigerated air therethrough by a suitable air moving means such as a blower. As shown in FIGS. 1 and 2 of the drawings between the rear wall liner 23 and a forwardly spaced cover plate 24 there is provided a centrifugal fan housing 25 having in its front wall an inlet opening 26. Within the housing 25 is a centrifugal fan 27 driven by an electric motor 28 which protrudes from the rear wall 18. Extending downwardly from the fan housing at the rear of the freezer compartment 22 is a first cold air evaporator flow chamber 30 defined in part by the liner rear wall 23 and evaporator cover plate 32. Within the evaporator flow chamber 30, whose upper walls 29 converge to form inlet opening 26, is located a vertically finned air-cooling refrigerant evaporator 33 of customary construction.

As seen in FIG. 2 at the rear of the freezer compartment 22 there is provided an inwardly offset spaced duct front wall 34, defining an upwardly extending flow chamber or cold air supply duct 35 transversely defined between the liner side wall 31 and supply duct side wall 36. The duct 35 communicates with an upwardly discharging fan housing outlet 37 and terminates in a forwardly extending right angle portion 38 of duct 35 defined between the liner top wall 39 and forwardly extending channel 40 having a plurality of exit louvers 42 in order to provide exits for the cold air in the horizontally disposed angle duct 38. The circulated air is refrigerated by being passed in heat exchange relationship with the fin and tube evaporator 33, which is suitably refrigerated by conventional means, including a sealed motor-compressor unit 44. A condenser 46 is located on the back wall of the refrigerator cabinet between the cabinet rear wall 18 and an outer condenser cover plate assembly 48. The motor-compressor 44 is connected via a compressor refrigerant discharge line 52 to the condenser 46 while supply restriction line 53 connects the outlet of the condenser to the evaporator and suction return line 54 connects the evaporator to the compressor inlet. The refrigeration apparatus functions in a conventional manner to provide refrigerant fluid to the serpentine tube portion 56 of the evaporator.

A portion of the air circulated by the centrifugal fan 27 is divided or split off from the vertical delivery duct 35 into a horizontally disposed cross-over duct assembly 62 comprising a rectangular plastic tube which extends through the center partition 20 into the abovefreezing compartment 21 adjacent the top wall 12. The air exits the duct 62 and is diverted downwardly into the fresh food compartment 21 by a cover member 63 spaced outwardly from the liner rear wall 23 and suitably secured thereto. At the duct discharge end 64 damper means in the form of a butterfly damper 65 is located and is controlled thermostatically in accordance with the temperature of a thermostat bulb 66 located in compartment 21 so that the bulb is connected via tube 67 to bellows 68, which operates damper 65, is responsive to the temperature of the air therein. A conventional thermostat cold control is provided at 70 having bulb 69 adjacent evaporator 33 by tube 71 for regulating the operation of motor-compressor 44 on a cooling demand cycle. The discharge opening 64 may be louvered for directing the air from duct 62 to the chamber 21.

As seen in FIG. 1, in evaporator air bleeder or diverter duct 73 is branched or split off at exit duct 73 from the duct wall 36 for directing a portion of the cold air exiting from the evaporator 33 vertically downwardly to a frost eliminator section generally indicated at 76. Intermediate the duct exit 73 and the frost eliminator section 76 there is located an air return opening 78 in cover plate 23 for conveying the freezer compartment return air into vertical passage means 80, formed by enlarged duct portion 81 which circumscribes or surrounds the lower portion of air return duct 72, such that the return air is mixed or intermingled with the evaporator return air at the exit end 82 of the freezer air return duct 72.

As seen in FIGS. 1 and 3, an above-freezing air return passage is provided at 84 extending through a lower portion of the center partition wall 20. The passage 84 provides a fourth air return duct interconnecting the fresh food compartment 21 with the throat portion 86 of a vertically oriented Venturi mixing nozzle 88 located in the lower portion of the air return from the evaporator or second air return duct 72. The Venturi nozzle 88 has its upper converging portion or cone air entrance 90 positioned to receive a portion of the freezer air therein for discharge from lower diverging portion or cone air exit 92 such that an aspirator effect or predetermined suction is created at the throat 86 to aid in drawing above-freezing spent air from compartment 21 for mixture in the Venturi axial passage with the below-freezing third evaporator air return entering third entrance 78 and exiting at 82 from the third frozen food compartment cold air return duct 81.

As best seen in FIG. 3, an air combining or mixing chamber 94 is provided at the exit end 82 of enlarged return freezer air duct 81 disposed around the second bleeder air duct 72 in spaced relation from the outer walls thereof and whose left hand wall 96 is inwardly and downwardly sloped to exit 98 to provide a tapered cross-section toward the exit 98 and insure a streamlined flow of air through separator 100. The sloped wall 96 terminates in a sharply and outwardly curved fluted edge to form crystallized water separator means. In the preferred embodiment a snow comb separator 100 is provided with slotted openings 101 separating curved teeth 103 which as seen in FIG. 4 and FIG. 6 provide the centrifugal air flow removal of crystallized frozen water formed from the mixing in chamber 94 of the relatively moist above-freezing temperature air returning from freezer compartment 22.

Snow or crystallized water subjacent collector means is provided in the bottom wall 14 of the freezer compartment 22 and which in the disclosed form is a trough or receptacle 102 set flush with the bottom wall inner liner whose upper edge merges or blends with the sloped liner wall 93 and vertical liner 106 such that the snow or crystallized water comb separator is positioned in vertical alignment above trough 102. It will be noted that a horizontally disposed screen 108 is positioned adjacent the collector bottom wall 110 and that melted snow in the collector will drain therefrom through the drain tube 112 and check valve 114 (FIG. 1) into the defrost water drain pan 116 positioned in an ambient environment above the desuperheat coil 118 of the refrigeration system, where it will be evaporated there from by the heat of the ambient air and the desuperheat coil 118. The upright evaporator chamber 30 has a lower sloped wall 93 to define an air inlet 95 through which the air is drawn for passage over the upright evaporator 33.

As shown the wiring diagram of FIG. of the optional frost melt assist heater 150 is connected by conductor 151 from the supply conductors L to a first fixed off-cycle or warm contact 152 of cold control thermostat 70. The cold control includes a switch element 155 of the double throw type and normally connects through fixed contact 156 and conductors 157,

I58 to motor protector 160 and conductor 162 to freezer fan motor 28. The conductor 166 connects motor protector 160 to contact 168 of relay 170, while relay contact 172 is connected via conductor 174 to capacitor 176 which is in turn connected by conductor 178 to compressor motor 180 and thence by conductor 182 to supply line L It will be noted that center vertical mullion dryer 184 is connected via conductors I86 and 157 to cold control contact 156 such that it is energized only when the cold control element 155 contacts cold contact 156 during the cooling or run cycle of the refrigerator when the compressor motor 180 is running.

Additional heaters such as the butter conditioner 190 heater 191 and 192 are connected by slide switch 194 across the supply lines L L Refrigerator lamps 196 are energized by lamp switch 198 while freezer lamp 200 is energized by lamp switch 202.

As one example of a typical air flow distribution cycle for the disclosed form of the invention wherein the fan 27 delivers about cfm of cold air flows from the evaporator chamber 30. Of the total about 45 cfm of air or approximately 80 percent of the flow enters duct 35 and about 10 cfm or approximately 20 percent of the air flow is diverted into the inlet 73 of the bleeder duct 72. Of the 45 cfm in duct 35 about 40 cfm or approximately 70 percent of the air flow exits the freezer outlet 42 and about 5 cfm or approximately 10 percent of the air flow enters into the crossover duct 62 for exit from fresh food chamber outlet 64 with the damper in its open position. It will be noted that the damper 65 can be operated by any suitable means such as by a rack and pinion arrangement (not shown) controlled by the fluid motor bellows 68 as shown in U.S. Pat. No. 3,070,973 to J. J. OConnell and assigned to the assignee of the instant invention. In this way the percent of the evaporator air exiting outlet 42 enters freezer compartment air return inlet 78 while the 5 cfm of the cold air cools the fresh food compartment 21 and exits through return passage 84 into the throat of nozzle 88 for combining with the 10 cfm of bleeder air. The combined 15 cfm of mixed bleeder air and above freezing air exits at 83 to mix with the 40 cfm of frozen food compartment freezer air in chamber 94 whereby frozen crystals of moisture formed by the air mixture is settled or separated out by gravity and comb separator into collector trough 102 such that about 55 cfm of substantially moisture free predried air is drawn into the evaporator chamber 30 via its diverging entrance 95.

While the embodiment of the present invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted.

I claim:

1. A refrigerator comprising an insulated cabinet, an insulated vertical partition wall extending from top to bottom of said cabinet to provide separate vertical sideby-side fresh food and frozen food compartments, an upright evaporator chamber associated with the frozen food compartment rear wall containing an evaporator, a fan having an inlet connected to said evaporator chamber and having an outlet connected to both an upwardly extending cold air supply duct and a downwardly extending evaporator cold air diverter duct, 3 Venturi mixing nozzle located in said diverter duct, a frozen food compartment air return duct positioned in spaced relation around the lower portion of said diverter duct having its inlet disposed vertically below said fan, said air return duct defining a mixing chamber between the exit of said diverter duct and the bottom wall of said frozen food compartment. said cold air supply duct having an outlet for discharging part of the cold air therethrough, a crossover duct extending through the upper portion of said partition wall and having an air inlet communicating with said cold air supply duct and having an outlet for discharging a portion of the cold air into said fresh food compartment, thermostatically controlled damper means for controlling the flow of air from said crossover duct outlet to said fresh food compartment, passage means for returning air from the lower portion of said fresh food compartment to the throat portion of said Venturi nozzle, whereby below freezing diverter duct air flowing downwardly through said Venturi nozzle draws above freezing air from said fresh food compartment through said passage means into said throat for mixture with said air therewith, said air return duct having an outlet communicating with both subjacent crystallized water collecting means and the inlet of said evaporator chamber, whereby moisture in the combined return air is frozen by the diverter duct air flow while airborne, and means for separating the crystallized water from the combined return air during its flow from said mixing chamber for deposit into said collecting means prior to the combined return air flows being drawn upwardly into said evaporator chamber to minimize the formation of frost on said evaporator.

2. A refrigerator comprising an insulated cabinet, an insulated vertical partition wall extending from top to bottom of said cabinet to provide separate vertical sideby-side fresh food and frozen food compartments, an upright evaporator chamber associated with the frozen food compartment rear wall containing an upright evaporator, a single fan positioned about midway between the upper and lower walls of said frozen food compartment and having an inlet connected to said evaporator chamber and having an outlet connected to both an upwardly extending cold air supply duct and a downwardly extending evaporator cold air diverter duct, a Venturi mixing nozzle located in the lower portion of said diverter duct, a frozen food compartment air return duct positioned in spaced heat transfer relation surrounding the lower portion of said diverter duct having its inlet disposed vertically below said fan and vertically above said nozzle, said air return duct defining a mixing chamber between the exit of said diverter duct and the bottom wall of said frozen food compartment, said cold air supply duct having an outlet adjacent the frozen food compartment top wall for discharging part of the cold air therethrough, a crossover duct extending through the upper portion of said partition wall and having an air inlet communicating with said cold air supply duct and having an outlet for discharging a portion of the cold air into said fresh food compartment. a thermostatically controlled damper for controlling the flow of air from said crossover duct outlet to said fresh food compartment to maintain the air in said fresh food compartment above 32F. and the air in said frozen food compartment below 32F, a passage for returning air from the lower portion of said fresh food compartment to the throat portion of said Venturi nozzle, whereby below freezing diverter duct air flowing downwardly through said Venturi nozzle draws above freezing air from said fresh food compartment through said passage means into said throat for mixture therewith, said air return duct having an outlet communicating with both a subjacent crystallized water receptacle in the frozen food compartment bottom wall and the inlet of said evaporator chamber, whereby moisture in the combined return air of both the fresh food and freezer food compartments is frozen into crystallized water by the diverter duct air while airborne, and snow comb means for separating the crystallized water from the combined return air during its flow from said mixing chamber for deposit into said receptacle prior to the combined return air flow being drawn upwardly into said evaporator chamber so as to reduce the formation of frost on said evaporator, and means for melting and evaporating the water in an ambient environment outside said frozen food compartment.

3. A refrigerator comprising an insulated cabinet, an insulated vertical partition wall extending from top to bottom of said cabinet to provide separate vertical sideby-side fresh food and frozen food compartments, an upright evaporator chamber formed by a divider plate spaced from the rear wall of said frozen food compartment containing an evaporator with the plate extending substantially from the midpoint of the bottom of said frozen food compartment, said evaporator chamber defined in part by a vertical evaporator chamber side wall located intermediate the frozen food compartment liner side walls, the lower portion of said evaporator chamber side wall below said evaporator sloped toward said partition wall such that its free end terminates above a water collecting trough formed in the bottom wall of said frozen food compartment, said side wall free end terminating in a curled edge having a plurality of comb-like teeth, fan housing and duct means located in said evaporator chamber above said evaporator having an inlet communicating therewith and having an outlet connected to both an upwardly extending cold air supply duct and a downwardly extending evaporator air diverter duct, said cold air supply duct receiving approximately percent and said diverter duct receiving approximately 20 percent of the total flow from said evaporator chamber, a Venturi mixing nozzle located in the lower portion of said diverter duct, said diverter duct having its outlet spaced a defined distance above said water collecting trough, an enlarged frozen food compartment air return duct surrounding in spaced relation the lower portion of said diverter duct, said sloped portion of said evaporator side wall together with said partition wall forming in part an air mixing chamber having a tapered cross section to provide a streamlined flow of air through said teeth, said cold air supply duct having an outlet adjacent the frozen food compartment top wall for discharging the majority of the cold air therethrough, a horizontal crossover duct extending through the upper portion of said partition wall and having an air inlet communicating with said supply duct and having an outlet for discharging a minority of the cold air into said fresh food compartment, thermostatically controlled damper means for controlling the flow of air from said crossover duct outlet to said fresh food compartment, passage means for returning air from the lower portion of said fresh food compartment to the throat portion of said Venturi nozzle, the diverter air flowing through said Venturi nozzle drawing the fresh food compartment air through said passage means into said throat for mixture therewith,

3,893,307 7 8 said frozen food compartment return air duct having its the combined return air is predried prior to entering outlet defined 1 by said curled edge whereby the said evaporator chamber to minimize the formation of flow of return air redirected vertically upwardly to said evaporator while allowing gravitational flow of crystallized water into said subjacent trough, whereby 5 frost on said evaporator.

* i I I)! UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT N0. 3,893, 307

DATED 1 July 8, 1975 INVENTOROQ James W. Jacobs It is certified that error appears in the ab0ve-rdentified patent and that said Letters Patent are hereby corrected as shown below:

Column 1,

line 57, after "and" insert a line 60, after "doors" insert such Column 2, line 60, 73" (first occurrence) should be 72 line 66, "23" should be 32 Column 4, line 2, after "connects" insert the Signed and Sealed this thirteenth Day of April1976 [SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN AMP-fling Uffifl (mmm'ssinnvr of Pan-ms and Trurlwnurks 

1. A refrigerator comprising an insulated cabinet, an insulated vertical partition wall extending from top to bottom of said cabinet to provide separate vertical side-by-side fresh food and frozen food compartments, an upright evaporator chamber associated with the frozen food compartment rear wall containing an evaporator, a fan having an inlet connected to said evaporator chamber and having an outlet connected to both an upwardly extending cold air supply duct and a downwardly extending evaporator cold air diverter duct, a Venturi mixing nozzle located in said diverter duct, a frozen food compartment air return duct positioned in spaced relation around the lower portion of said diverter duct having its inlet disposed vertically below said fan, said air return duct defining a mixing chamber between the exit of said diverter duct and the bottom wall of said frozen food compartment, said cold air supply duct having an outlet for discharging part of the cold air therethrough, a crossover duct extending through the upper portion of said partition wall and having an air inlet communicating with said cold air supply duct and having an outlet for discharging a portion of the cold air into said fresh food compartment, thermostatically controlled damper means for controlling the flow of air from said crossover duct outlet to said fresh food compartment, passage means for returning air from the lower portion of said fresh food compartment to the throat portion of said Venturi nozzle, whereby below freezing diverter duct air flowing downwardly through said Venturi nozzle draws above freezing air from said fresh food compartment through said passage means into said throat for mixture with said air therewith, said air return duct having an outlet communicating with both subjacent crystallized water collecting means and the inlet of said evaporator chamber, whereby moisture in the combined return air is frozen by the diverter duct air flow while airborne, and means for separating the crystallized water from the combined return air during its flow from said mixing chamber for deposit into said collecting means prior to the combined return air flows being drawn upwardly into said evaporator chamber to minimize the formation of frost on said evaporator.
 2. A refrigerator comprising an insulated cabinet, an insulated vertical partition wall extending from top to bottom of said cabinet to provide separate vertical side-by-side fresh food and frozen food compartments, an upright evaporator chamber associated with the frozen food compartment rear wall containing an upright evaporator, a single fan positioned about midway between the upper and lower walls of said frozen food compartment and having an inlet connected to said evaporator chamber and having an outlet connected to both an upwardly extending cold air supply duct and a downwardly extending evaporator cold air diverter duct, a Venturi mixing nozzle located in the lower portion of said diverter duct, a frozen food compartment air return duct positioned in spaced heat transfer relation surrounding the lower portion of said diverter duct having its inlet disposed vertically below said fan and vertically above said nozzle, said air return duct defining a mixing chamber between the exit of said diverter duct and the bottom wall of said frozen food compartment, said cold air supply duct having an outlet adjacent the frozen food compartment top wall for discharging part of the cold air therethrough, a crossover duct extending through the upper portion of said partition wall and having an air inlet communicating with said cold air supply duct and having an outlet for discharging a portion of the cold air into said fresh food compartment, a thermostatically controlled damper for controlling the flow of air from said crossover duct outlet to said fresh food compartment to maintain the air in said fresh food compartment above 32*F. and the air in said frozen food compartment below 32*F., a passage for returning air from the lower portion of said fresh food compartment to the throat portion of said Venturi nozzle, whereby below freezing diverter duct air flowing downwardly through said Venturi nozzle draws above freezing air from said fresh food compartment through said passage means into said throat for mixture therewith, said air return duct having an outlet communicating with both a subjacent crystallized water receptacle in the frozen food compartment bottom wall and the inlet of said evaporator chamber, whereby moisture in the combined return air of both the fresh food and freezer food compartments is frozen into crystallized water by the diverter duct air while airborne, and snow comb means for separating the crystallized water from the combined return air during its flow from said mixing chamber for deposit into said receptacle prior to the combined return air flow being drawn upwardly into said evaporator chamber so as to reduce the formation of frost on said evaporator, and means for melting and evaporating the water in an ambient environment outside said frozen food compartment.
 3. A refrigerator comprising an insulated cabinet, an insulated vertical partition wall extending from top to bottom of said cabinet to provide separate vertical side-by-side fresh food and frozen food compartments, an upright evaporator chamber formed by a divider plate spaced from the rear wall of said frozen food compartment containing an evaporator with the plate extending substantially from the midpoint of the bottom of said frozen food compartment, said evaporator chamber defined in part by a vertical evaporator chamber side wall located intermediate the frozen food compartment liner side walls, the lower portion of said evaporator chamber side wall below said evaporator sloped toward said partition wall such that its free end terminates above a water collecting trough formed in the bottom wall of said frozen food compartment, said side wall free end terminating in a curled edge having a plurality of comb-like teeth, fan housing and duct means located in said evaporator chamber above said evaporator having an inlet communicating therewith and having an outlet connected to both an upwardly extending cold air supply duct and a downwardly extending evaporator air diverter duct, said cold air supply duct receiving approximately 80 percent and said diverter duct receiving approximately 20 percent of the total flow from said evaporator chamber, a Venturi mixing nozzle located in the lower portion of said diverter duct, said diverter duct having its outlet spaced a defined distance above said water collecting trough, an enlarged frozen food compartment air return duct surrounding in spaced relation the lower portion of said diverter duct, said sloped portion of said evaporator side wall together with said partition wall forming in part an air mixing chamber having a tapered cross section to provide a streamlined flow of air through said teeth, said cold air supply duct having an outlet adjacent the frozen food compartment top wall for discharging the majority of the cold air therethrough, a horizontal crossover duct extending through the upper portion of said partition wall and having an air inlet communicating with said supply duct and having an outlet for discharging a minority of the cold air into said fresh food compartment, thermostatically controlled damper means for controlling the flow of air from said crossover duct outlet to said fresh food compartment, passage means for returning air from the lower portion of said fresh food compartment to the throat portion of said Venturi nozzle, the diverter air flowing through said Venturi nozzle drawing the fresh food compartment air through said passage means into said throat for mixture therewith, said frozen food compartment return air duct having its outlet defined in part by said curled edge whereby the flow of return air is redirected vertically upwardly to said evaporator while allowing gravitational flow of crystallized water into said subjacent trough, whereby the combined return air is predried prior to entering said evaporator chamber to minimize the formation of frost on said evaporator. 